Whereas Spain and Italy are clear geographical regions, defined in the north by mountain ranges, the third peninsula projecting south into the Mediterranean is more amorphous. The Adriatic and Ionian seas define the Balkan peninsula on the west, and the Aegean and the Black Sea on the east. But to the north lie open plains (admittedly crossed by the Balkan range of mountains, but these have never proved much of a barrier). The line of the Danube is often taken as the northern boundary of the region.

Through these open plains there have swept successive waves of people pressing into Europe from Asia, whether arriving from Anatolia or along the steppes north of the Black Sea.

The Greeks are among the first known tribes to move south through the Balkans, nearly 3000 years ago. In the great movements of people in the early Christian centuries, the Goths and Huns and Slavs all pass this way, some of them settling. This has been an area where energetic tribes confront settled civilizations. It has also been where civilizations clash.

In classical times the Balkans are at the heart of a single Greco-Roman civilization. But later they have been a troubled interface - between Roman and Greek Christianity, and between Christianity and Islam. They have been a seismic fault between Europe and Asia.

The Slavs in eastern Europe: from the 6th century

The Slavs are first referred to by this name in518 when they press into the Roman empire across the Danube, though they have been settled for more than a millennium in the region to the north (between the Vistula and Dnieper rivers).

After the collapse of the empire of the Huns, in the 5th century, the Slavs begin to expand their territory. They move west into what are now the Czech republic and Slovakia and south towards the Adriatic and Aegean - where their separate regional and religious development as Slovenes, Croats, Serbs, Macedonians and Bulgarians later makes the peninsula of the Balkans one of the most politically complex regions on the face of the earth.

Greece unsettled: 11th - 13th century

The position of Greece, as a central region of the Byzantine empire, remains reasonably secure until the 11th century. At that time, and in the following century, there are troublesome attacks on the Greek coastline from the Normans of Sicily. But the real upheaval, throughout the Balkans, comes in the early 13th century after the capture of Constantinople by the fourth crusade.

The invading Latins seize kingdoms in the Balkans. The Venetians establish settlements along the coast. When the Byzantine emperors reassert themselves, later in the century, this becomes a hotly disputed region. It remains so, in the 14th century, with the arrival of new intruders - the Ottoman Turks.